m and m 13 - Anticholinergic Drugs Flashcards
What cholinergic receptor subtype to atropine, scopolamine and glycopyrrolate target?
Antimuscarinic receptors
What are the two functional groups present on anticholinergics? What is the bond type linking these 2 functional groups?
Aromatic acid and organic base linked with ester bond
What are he 3 muscarinic receptor subtypes and their locations?
M1 - Neuronal
M2 - Cardiac
M3 - Glandular
What happens as you go higher than the normal clinical doses for the antimuscarinic agents?
Start to lose specificity
What is the effects of antimuscarinics on CV function (re: AV node and PR interval)? What happens with low doses of atropine?
Increases conduction through AV node and shortens the PR interval
Low dose atropine causes paradoxical bradycardia
What is the effect of antimuscarinics on ventricular function?
Usually no effect
What is the possible CV side effect of antimuscarinics?
Can cause atrial arrythmias and nodal (junctional rhythms
Whats is the significance of antimuscarinics and presynaptic muscarinic receptors?
Presynaptic muscarinic receptors inhibit Norepi release, therefore antimuscarinics will increase NE release
Usually, antimuscarinics don’f affect the peripheral vasculature. What is the exception?
Atropine in large doses can cause dilation of cutaneous blood vessels, causing atropine flush
What is the effect of antimuscarinics on respiratory secretions and dead space (mechanism of latter)?
WIll decrease secretions and increase dead space (secondary to relaxation of the bronchial smooth muscle relaxation)
Signs of antimuscarinics cerebral excitation include? (3)
Excitation, restlessness and hallucinations
Signs of antimuscarinics cerebral depression include? (2)
Sedation and amnesia
What is the medication that is particularly good at reversing cerebral effects of antimuscarinics?
Physostigmine - can cross BBB
WHat is the effects of antimuscarinics on gastric secretions, motility and the LES?
Decreased secretions
Decreased motility
Decreased pressure in the LES
What are the two effects of antimuscarinics on the eye?
Mydriasis (pupilary dilation)
Cycloplegia (inability to accomodate to near vision)
True or false, acute angle glaucoma is common side effect of systemic antimuscarinics
False - not after systemic administration *** check this
What is the effect of antimuscarinics on the GU system? Mechanism?
Will cause relaxation of bladder smooth muscle and cause urinary retention
What is the effect of antimuscarinics on sweat glands? What is the “syndrome”?
Can inhibit sweat glands, block thermoregulation leading to “atropine fever”
True or false, atropine is a quaternary amine?
False, tertiary amine
What is the most efficacious anticholinergic for treating bradyarrythmias? What group of patients should not get atropine?
Atropine
Avoid in patients with CAD - might not tolerate the tachycardia and increase O2 demand
How is atropine related to ipratropium? What property of ipratropium makes it good for treating lung pathology?
Ipratropium is a derivative of atropine, a a quaternary ammonium structure. This prevents systemic absorption when used in lungs
How is scopolamine structurally different from atropine?
Has an epoxide on the heterocyclic ring
Which is a more potent antisialagogue, atropine or scopolamine? Which is more likely to cause CNS effects?
Scopolamine for both
Why is scopolamine useful as a transdermal agent? What are 2 possible uses?
It is lipid soluble
Used for PONV and motion sickness
What types of patients is scopolamine contraindicated in, i,e. what pathology?
Closed angle glaucoma
How is glycopyrolate different from atropine?
It has a quatenary amine, has both a cyclopentane and pyridine moiety
What are the 2 major uses of glycopyrolate?
Decreased salivary and respiratory gland secretions
What route of administration is associated with increased HR after glycopyrrolate admin?
IV but not IM.
What other drug classes will predispose patients to anticholinergic syndrome?
TCAs
Antihistamines
Antipsychotics
(All have anticholinergic effects)
Neostigmine, pyridostigmine, physostigmine and edrophonium are all cholinesterase blockers. Which is best for reversing anticholinergic toxicity and why?
Physostigmine - only one that isnt quaternary amine and can cross the BBB
